Motor powered catamaran

ABSTRACT

A twin-hulled water craft or catamaran preferably has rotationally molded plastics hulls ( 1 ) and pod ( 2 ) preferably with provision for fore and aft adjustment of the hulls with respect to the pod. The craft is hand-steered and preferably hand accelerated. Propulsion is via either an inboard or outboard motor with propeller or water-jet. The rider or riders sit low in the pod behind the steering control and above or before the motor. The hulls ( 1 ) are shaped to minimize spray in front of the rider and to allow easy outward sideways skidding. The construction seeks to improve the handling, stability and speed characteristics of this type of craft.

TECHNICAL FIELD

[0001] The invention relates to motor powered twin-hulled or catamaran surface craft which include a central pod or body portion mounted between two pontoon hulls.

[0002] It is well recognised that the performance of catamaran-type water craft can be superior to that of a mono-hulled craft, when fitted with a similar sized engine. Craft of the catamaran type usually exhibit a greater stability while having a smaller wetted surface area and hence can achieve greater speed.

BACKGROUND ART

[0003] A known powered small catamaran has wide hulls (for lateral stability) with the rider sitting high in a position above an “outboard” motor but the high centre of gravity detracts from stability and necessitates the use of wide hulls which do not have good handling or speed characteristics.

[0004] The object of the present invention is to provide an improved craft with better stability and handling characteristics.

DISCLOSURE OF INVENTION

[0005] The present invention consists in a twin-hulled water craft, for operation on the surface of a body of water, comprising two hulls each mounted to a pod located between the two hulls, the pod including rider accommodation means for accommodating a rider of the craft in use and adapted to be provided with suitable motorised propulsion means to power the craft in use characterised in that the pod includes control means located forward of the rider accommodation means and adapted in use to be hand operated by the rider to enable steering of the craft via steering means with which the control means coacts, said control means also being operable to vary the speed of propulsion in use, the accommodation means including seating means for the rider and the whole or substantially the whole of the length of each hull which is or may be underwater in use having no pod-facing or inward surface angled to produce a bow-wave directed to the opposite hull in use and each such part of the length having its outward surface shaped to facilitate sideways outward skidding of that hull in use.

[0006] Preferably the propulsion means when fitted is an outboard motor and mounting means provided on the pod includes a transom to which the outboard motor can be mounted in a position aft of the rider so that a seated rider's weight may be kept low between the motor and the control means.

[0007] However, an internal motor may be provided under the seating means driving a propeller or water-jet propulsion unit with appropriate provision for steering.

[0008] Preferably, the lower part of said hull length is substantially V-shaped with the pair of catamaran hulls resembling a conventional V-hull split longitudinally down the middle.

[0009] Preferably the inward surface of said V-shaped cross-section is substantially vertical or opposite hulls are inclined closer at the bottom than the top so that there is no, or minimal, tendency for spray to be generated in front of the pod.

[0010] Preferably, each hull is independently, or as a pair, adjustable to, and fixable at, any one of two or more discrete predetermined lengthwise positions relative to the pod.

DRAWINGS DESCRIPTION

[0011] The above gives a broad description of the present invention, preferred forms of which will now be described with reference to the accompanying drawings in which:

[0012]FIG. 1 shows a view of the catamaran of one possible form of the invention, as seen from the port, or left, side with provision for fore and aft adjustment of the hull position with respect to the pod. The control means is not shown nor is the motor;

[0013]FIG. 2 shows a plan view, from below, of the catamaran shown in FIG. 1;

[0014]FIG. 3 shows an end view, as seen from aft, of the catamaran shown in FIGS. 1 and 2;

[0015]FIG. 4 shows a cross-sectional view of the right (or starboard) hull and a fragment of the pod, as seen from aft, showing a second possible manner of fixing the hull to the pod. The hatched part should be understood to be hollow;

[0016]FIG. 5 shows a cross-section view of the right (or starboard) hull and a fragment of the pod, as seen from aft, showing a third possible manner of fixing the starboard hull to the pod. Again the hatched part is hollow;

[0017]FIG. 6 shows a rear perspective view of part of the port hull of the type shown in FIG. 4 and

[0018]FIG. 7 shows a front perspective view of part of the starboard hull of the type shown in FIG. 4.

DESCRIPTION OF BEST MODES

[0019] The catamaran of the current invention, as seen in FIGS. 1 to 3, has three main parts, which parts are discrete and are made separately: the central pod 2, and the port and the starboard hulls 1. The pod 2 and hulls 1 are mounted in a configuration such that when the craft is sitting or riding on a body of smooth water, the pod is above and clear of the surface of the body of water when the craft is not overloaded. There is no platform forward of the pod to be caught by wind or waves and this helps prevent backward flipping of the craft, although a net can be strung between the hulls forward of the pod to carry equipment, or a stretcher could be clipped across the hulls, or a small bin for an anchor or fishing gear could be provided forward of the pod.

[0020] The craft is powered by a motorised propulsion unit, preferably an outboard motor. In use, the motor is mounted on the central pod 2, either attached to a transom or stern 10 of the pod or in a well (not shown) in the pod.

[0021] The motor may, however, be provided under the rider's seat 6 and may provide inboard drive to a stern propeller or a water-jet unit with suitable provision for steering in such case.

[0022] The central pod is preferably a one-piece plastic moulding, perhaps a one-piece polyethylene rotationally moulded component with its parting line being at or near the horizontal plane 33 shown in FIG. 1, although it may be made from a solid material, eg aluminium, timber, fibreglass or plastic. The hulls may be either rigid or flexible and inflatable, or a combination of both. They are preferably likewise rotationally moulded with a major parting line mostly in the horizontal plane 34 in the case of the embodiment of FIG. 5. However the parting line is more complex at the fore of each hull, which is shaped to direct spray outward and downward as shown in FIG. 7, so that the parting line tilts upwards to follow the lip such as 35 in FIG. 2 and an eye 36 is formed to facilitate forward tethering or towing of the craft. At the rear a third or end mould enables a drain bung-hole 37 and horizontal handle 38 to be moulded as an integral part of each hull as shown in FIG. 6. Also a rear tie down or tethering hole 39 and cleat 40 may be provided at each side.

[0023] The central pod includes an accommodation means to accommodate a rider or preferably two or more riders. Preferably, the rider is accommodated behind a splash guard 8 located at the forward end of the pod. Steering is by hand operated control means (not shown) such as a steering wheel or handlebars mounted on the pedestal 7. The control means coacts with steering means linkages or cables to turn a rudder, turn the propeller axis or water-jet thrust as appropriate. The control means also includes a hand control for varying the motor speed. This may be a lever on the handlebar if provided. A foot accelerator could be used, especially where steering was by means of a wheel.

[0024] The seating means 6 may accommodate one, two, or more persons sitting astride the seat in a fore and aft line. The pod may include two foot wells, not shown, one on each side of such a central seat, providing space to accommodate the feet of a rider or riders standing or sitting astride the fore and aft seat. During use of the craft, when an outboard motor is mounted in a position aft of the seat this allows the centre of gravity of the rider or riders to be maintained relatively close to the surface of water. The space under the seat can be used for steering means and accelerator controls and suspended above that one or more removable gear containers. The lid of such containers may be a padded and removable seat unit, perhaps held in place by elastic cord.

[0025] The mounting of each hull to the pod preferably allows adjustment of the fore and aft position of the hulls relative to the pod. Preferably, the hulls 1 are attached to the central pod 2 by a slide system that allows for a range of fore and aft adjustment, while restricting sideways and vertical movement.

[0026] For example in FIGS. 1 and 2 the pod includes slides 11, 12 which have holes that fit around and slide in a fore and aft direction along elongate rails 3, 4, preferably stainless steel tubes, that are fixed to, but spaced from, the hulls.

[0027] In the embodiment shown in FIGS. 1, 2 and 3, the central pod 2 has an upper pod slide 12 provided at each corner of the pod; ie in spaced fore and aft positions on each side of the pod. These upper pod slides 12 fit over and slide along an upper slide rail 3 attached to the top of each hull, as will be explained in more detail below. Lower pod slides 11 are provided at each lower corner of the pod; ie in spaced fore and aft positions on each side of, and at the underside of the pod. These lower pod slides fit over and slide along an inner slide rail 4 attached to the inward facing surface of each hull, as will be explained in more detail below. The pod slides are preferably formed integrally with the pod, as shown in FIGS. 1, 2 and 3. Preferably the slides are integrally moulded with the pod as a one-piece moulded unit. Alternatively, they may be manufactured separately and bolted, screwed, riveted, glued, or otherwise fixed to the pod.

[0028] The upper pod slides 12 are retained in sliding engagement on an elongate upper slide rail 3, which is provided by a rod, pipe or tube, for example. The upper rail is mounted near the inward edge of the topside of a hull and is fixed to the hull by upper hull fixing brackets 5U. The lower pod slides 11 are retained in sliding engagement on an inner slide rail 4 provided by a second elongate element, such as a rod, pipe or tube, mounted on the inward facing surface of a hull by lower hull fixing brackets 5L. Each pod slide 11, 12 is slidingly fitted to a corresponding slide rail, between at least two adjacent hull fixing brackets. The upper and lower hull fixing brackets 5U, 5L are each provided with an aperture in which a rail may be fitted when fixing the rail to a hull. The upper and lower hull fixing brackets 5U, 5L may be formed integrally with a hull or may be bolted, screwed, riveted, glued, or otherwise fixed to the hull.

[0029] In the arrangement shown in FIGS. 1, 2 and 3, there are two upper and two lower pod slides on each side of the pod, and each hull has three upper fixing brackets on the upper surface of the hull and three lower fixing brackets on the inward facing surface of the hull.

[0030] In the embodiments shown in FIGS. 4 and 5, the central pod has a constant cross-section, concave portion extending in a fore and aft direction along each side. FIGS. 4 and 5 show cross-sectional views of the starboard hull mounted for sliding engagement with the constant cross-section, concave portion on the starboard side of the pod. The port hull, not shown, is mounted similarly, in a symmetrical, mirror image, arrangement.

[0031] In the arrangements shown in FIGS. 4 and 5 the hull is shaped with a constant transverse cross-section over a major middle portion of its length. The constant cross-section portion of the hull includes an upper portion shaped to conform to, and fit within, the constant cross-sectioned, concave portion of the central pod.

[0032] In the arrangement shown in FIG. 4, the concave portions along the sides of the pod face downward and outward. The hulls each have a constant cross-sectioned portion that conforms with and fits within a matching concave section at the side of the pod.

[0033] In the preferred arrangement shown in FIG. 4, the previously described upper slide and rail arrangement is substituted by inter-engaging strips. A first strip 24 is formed with an L-shaped cross-section and is attached to the outer edge of the pod 2. The first strip is preferably provided in two portions: one fitted adjacent the upper fore corner of the pod, the other adjacent at the upper aft corner of the pod. The first strip, or each first strip portion, engages an outwardly projecting portion of a second strip 25 which is attached to a flattened area formed on the upper surface of the hull 1. The first and second strips are preferably metal and preferably stainless steel. The first strip, or each first strip portion, is attached to the pod by fixings 23, such as screws or rivets, or their equivalents. The second strip is also attached to the hull by fixings, such as screws or rivets, or their equivalents.

[0034] In the arrangement shown in FIG. 4 the hull is fixed in a selected fore and aft position by winged and threaded bolt 30 which is fitted through a hole 41 moulded in the pod to engage one of a series of threaded holes 32 in strip 25. The series of holes 32 allows the hull to be fixed in any one of a range of positions.

[0035] Hull fixing brackets 20 (shown by dotted lines in FIG. 4) are attached at intervals along the inward facing side of the hull. An elongate rail element 4 is fixed to each hull 1 by at least two, and preferably four, hull fixing brackets 20. Apertured sliding pod brackets 28, preferably integrally moulded with the pod at fore and aft ends of the side edges of the underside of the pod, are slidingly retained on the elongate rail elements. The hull fixing brackets 20 may be formed integrally with a hull or may be provided as separate metal fittings fixed to the hull by adhesive or by fixings (not shown in FIG. 4), such as bolts, screws or rivets, or their equivalents. The pod sliding brackets 28, although preferably formed as an integral part of the pod, may be formed as discrete elements and fixed to the pod such as by adhesives, bolts, screws or rivets, or their equivalents.

[0036] The upper part of each hull may be cut to provide an access hatch (not shown) after moulding and internal reinforcement may be provided to each hull to transmit loads from the brackets 20 to the bottom of the hull. This reinforcement may be wooden. The access hatch may be permanently sealed or welded shut after the reinforcement has been placed and it is normally concealed by the pod.

[0037] In the arrangement shown in FIG. 5, the concave portions along the sides of the pod face downward. The constant cross-section of each hull includes two steps 19 which engage strips 21 fixed to the underside of the pod along each edge of the constant cross-section concave portion. The strips retain the hull in close sliding engagement with the pod. The strips, which are preferably stainless steel, are attached to the pod by fixings 18, such as screws or rivets.

[0038] In the arrangement shown in FIG. 5 the hull is fixed in a selected fore and aft position by winged and threaded bolt 30 which is fitted through a hole in the pod to engage one of a series of threaded holes 31 moulded in the hull. The series of holes 31 allows the hull to be fixed in any one of a range of positions.

[0039] The hulls can be fixed in any one of two or more predetermined positions relative to the pod. The hull position relative to the central pod is adjusted and then locked, e.g. at a position that takes account of the power and weight of the motor used or to be fitted.

[0040] The whole or substantially the whole of the length of each hull which is or may be underwater in use has no pod-facing or inward surface angled to produce a bow-wave directed to the opposite hull in use and each such part of the length has its outward surface shaped to facilitate sideways outward skidding of that hull in use. Thus the hulls have an asymmetric transverse cross-section that is substantially constant along a large middle portion of their length. Preferably, and as best seen in FIGS. 4 and 5, the cross-section of the hulls at least below the waterline is substantially V-shaped and is such that the inward-facing surface 13 below the waterline is substantially vertical. This arrangement reduces the amount of spray and water deflected inwardly toward the riders of the catamaran when it is underway. In contrast, the outward facing surface 14 below the waterline is inclined outwardly and upwardly from the lowest point of the hull. This surface deflects spray and water outwardly away from the riders of the catamaran when it is underway. This asymmetrical transverse cross-section also helps to improve the stability and handling characteristics and provides an improved performance particularly when the catamaran is cornering or is sideways on to a wave when the shape helps minimise the risk of flipping sideways.

[0041] The two arms of the V-shaped transverse cross-section of the hulls are preferably straight providing the large middle section of the length of the hulls with substantially flat surfaces below the waterline. The V-shape may include inwardly or outwardly curved arms or it may be truncated or rounded at the lowest point.

[0042] The two hulls of the catamaran are usually positioned at similar fore and aft positions relative to the pod. This helps keep the handling characteristics of the catamaran symmetrical and independent of the direction of turning.

[0043] Alternatively, it may be desirable to position the two hulls at different fore-aft positions, relative to the central pod, so that the handling characteristics of the catamaran are asymmetrical. For example, the handling characteristics may be optimized for turning in a particular direction. This may be desirable in certain situations. For example, the hulls may be preset to different fore-aft positions when ‘tuning’ a catamaran for a particular course that requires the catamaran to negotiate a predominance of turns in one direction (as in a generally circular racing track).

[0044] The provision of fore and aft adjustment allows the trim of the craft to be optimised for a variety of load distributions. However, the pod could be fixed in position to the hulls where the load variables were small. This would provide a cheaper craft where such a compromise proved possible.

[0045] The pod described above is a one-piece construction to which the two hulls are separately attached. Alternatively, the pod may be a two-piece construction. In this two-piece pod arrangement an inner pod part is adjustably mounted to an outer pod part, and each of the two hulls is attached to the outer pod part in a fixed position. The inner pod part may accommodate the driver and any crew or passengers. The two hulls and the outer pod part together as a unit are adjustable relative to the inner pod part to provide the adjustment of fore and aft trim.

[0046] In the two-piece pod arrangement the motor powering the catamaran and the drive unit, such as a propeller system or jet unit, may be mounted on or in the inner or outer pod part. Preferably, the motor and drive unit are included in the inner pod part to help maximise that weight of the part of the catamaran that is moved relative to the hulls. This increases the effect on the fore and aft trim that a given change in relative positioning provides.

[0047] Where an outboard motor is used the underside of the pod may be equipped with a V-shaped part, the apex towards the front of the craft, to get a flow of clean water onto the outboard leg. This device is centrally mounted at the stern with its lower edge below the cavitation plate of the outboard motor.

[0048] A trim tab may also be fitted to a hull to counter the torque produced by the motor on the pod. This keeps the hulls evenly immersed. The best place for this is at the aft of the left hull on the inward side where damage is less likely. The tap comprises a horizontal plate suitably pivoted to the inward hull wall and having adjustment means to enable its ramp angle to the longitudinal line of its hull to be adjusted, preferably while on the move, to allow alteration of the upthrust the tab provides. 

1. A twin-hulled water craft, for operation on the surface of a body of water, comprising two hulls (1) each mounted to a pod (2) located between the two hulls, the pod including rider accommodation means for accommodating a rider of the craft and adapted to be provided with suitable motorised propulsion means to power the craft in use characterised in that the pod includes control means located forward of the rider accommodation means and adapted in use to be hand operated by the rider to enable steering of the craft via steering means with which the control means coacts, said control means also being operable to vary the speed of propulsion in use, the accommodation means including seating means (6) for the rider and the whole or substantially the whole of the length of each hull which is or may be underwater in use having no pod-facing or inward surface angled to produce a bow-wave directed to the opposite hull in use and each such part of the length having its outward surface shaped to facilitate sideways outward skidding of that hull in use.
 2. A twin-hulled water craft as claimed in claim 1 characterised in that the seating means (6) provides an openable lid of a compartment.
 3. A twin-hulled water craft as claimed in claim 1 or claim 2 characterised in that the seating means (6) provides fore and aft directed bench seating for 2 riders.
 4. A twin-hulled water craft as claimed in any one of the preceding claims characterised in that the control means includes handlebar-type steering and a hand accelerator.
 5. A twin-hulled water craft as claimed in any one of the preceding claims characterised in that part of the steering means is located beneath the seating means (6).
 6. A twin-hulled water craft as claimed in any one of the preceding claims characterised in that the pod (2) and hulls (1) are each separately moulded in plastics.
 7. A twin-hulled water craft as claimed in any one of the preceding claims characterised in that the hulls (1) are attached to the pod (2) in a manner allowing fore and aft positioning movement with respect to the pod (2). 